This invention relates to a developer cartridge, an image forming unit and an image forming apparatus.
In a conventional electrophotographic image forming apparatus such as a printer, a copier, a facsimile, a combined machine or the like (for example, a printer), a surface of a photosensitive drum is uniformly charged by a charging roller. The surface of the photosensitive drum is exposed to the light by means of an LED head so that a latent image is formed thereon. The latent image is developed with toner (i.e., developer) that forms a thin layer on a developing roller and adheres to the latent image with static electricity. The developed image (i.e., toner image) is transferred to a recording medium by means of a transferring roller, and is fixed to the recording medium by means of a fixing device. After the transferring, the toner remaining on the photosensitive drum is removed by a cleaning blade.
The above described photosensitive drum, the charging roller, the developing roller, the cleaning blade and the like are integrated into one unit as an image forming unit (also referred to as an ID unit, a developing device or the like). A developer cartridge is constructed as a separate unit mountable to a main body of the image forming unit. When the toner in the image forming unit decreases after the printing operation is repeated, the developer cartridge is replaced for supplying the toner to the image forming unit.
The developer cartridge has a toner supplying opening formed on a position corresponding to a toner receiving opening formed on the main body of the image forming unit. The developer cartridge also has a shutter portion for opening and closing the toner supplying opening. An operation lever is provided on an end of the developer cartridge and is integrally formed with the shutter portion. When the operation lever is rotated, a rib formed on the main body of the image forming unit is guided by a guide groove formed on the operation lever, and the developer cartridge is mounted to the main body of the image forming unit. In this state, the toner can be supplied to the main body of the image forming unit. Such a printer is disclosed in, for example, Japanese Laid-Open Patent Publication No. 11-133713.
However, in the conventional printer, when the image forming unit is packed and shipped in such a manner that the developer cartridge is mounted to the main body of the image forming unit, there is a possibility that the toner may leak outside through a joint portion between the toner cartridge and the main body of the image forming unit during transport.
Accordingly, the image forming unit and the developer cartridge are individually packed and shipped, and therefore costs of the image forming unit and the printer (i.e., the image forming apparatus) increase.